Sintering apparatus



May 11, 1948. A. w. BABB 2,441,383

SINTERING APPARATUS Filed Aug. 28, 1943 I v INVENTOR. ALF/Em W-BA BB ATTORNEYS Patented May 11, 1948 UNITED, STATES PATENT OFFICE SINTEBING APPARATUS Alfred W. Babb, Cleveland, Ohio Application August 28, 1943, Serial No. 500,388

1 Claim.

This invention relates generally to the art of sintering and particularly to a new and improved method of, and to new and improved apparatus for, sintering by which the sizes of the pieces of sintered material may be controlled.

Fine materials, such as ironore, flue dust an the like have been sintered heretofore by the steps of mixing them with fine, combustible material such as coal, coke and the like, charging the mixture onto pallets of a sintering machine, igniting the combustible material, and drawing air therethru until the combustible material was more or less completely burned. Then the highly heated and usually still burning sinter was discharged from the pallets. Frequently this sinter was then cooled by spraying water onto it.

Since the temperature attained by the burning part of the charge is as much as about 1000 F. and since the burning progresses down from the top surface of the charge, the temperature of the entire charge is still quite high when combustion is practically completed, the upper layers being somewhat cooler than the lowest layer.

The effect of suddenly cooling the hot sinter with water was that the sintered clusters are disintegrated and in many instances as much as 90% of the sintered material was less than about 1" in size. I believe that when water came into contact with the sinter which was highly heated, for example, at about 1000" F. or even at lower temperatures down to about 250 F., the friable, porous sinter was broken, thus accounting for the high percentage of small sized particles in the water-quenched product. While such small sized material is suitable for charging into blast furnaces, it is not desirable for charging into open hearth furnaces where a much larger percentage of the material should be 1" or larger in size.

I have discovered that when hot sintered ma terial is cooled on the pallets by the passage of air the'rethru, the amount of pieces larger than about 1" in sizemay be greatly increased; as much as 70% or more of the sintered product being larger than 1" in size. I have also discovered that by controlling the amount and/or pressure of air. which is used for cooling the hot sinter, it is possible not only to control the size of the cooled particles but also to obtain stronger particles and thus adapt the product to various intended uses. I believe that the particles are strong because they are cooled thru the temperature in which they have little strength without weakening them and when this cooling is completed they possess an unweakened structure which is quite strong.

The method of the present invention, briefly stated, comprises the steps of charging a mixture of fine material to be sintered and fine combustible material onto a pallet of a sintering machine, igniting and burning substantially all the combustible material in the mixture, then drawing air thru the highly heated sinter and reducing its temperature, and then discharging the thus cooled material from the pallet. The apparatus embodying the present invention may be briefly described as comprising a sintering machine having pallets, means to charge onto the pallets a mixture of fine material to be sintered and fine combustible material, means to ignite the mixture, means to draw air thru the burning mixture and means to draw air thru the resulting sinter to cool the same before it is discharged from the pallets, and means for regulating the amount of air which is drawn thru the sintered material.

In the drawings accompanying and forming a part of this specification, v

Figure 1 is a diagrammatic, side elevational view, illustrating one form of apparatus embodying the present invention; and

Figure 2 is a view showing a modification of the suction apparatus of Fig. 1.

Fig. 1 shows a sintering machine of the Dwight lg: Lloyd endless track type. This machine comprises -a plurality of pallets I which are movable around a closed path defined by rails or track la which support and guide the pallets. A charging hopper 2 is disposed above the pallets at one end of the track to load charges of finely divided combustiblematerial and material to be sintered onto the pallets I as they pass therebeneath. An ignition furnace 3 of suitable form is provided adjacent to the hopper 2 to ignite the'combustible material in the mixture on the pallets as they come therebeneath. A plurality of the usual suction boxes 4 is disposedbeneath the pallets and'with their open tops closely adjacent to the under sides of the pallets. These suction boxes 4 extend for the full width of the pallets and extend along the tracks for a-distance substantially equal to the distance thru which the pallets travel while substantially all the combustible material in the mixture is burning. These boxes 4 are connected to a manifold 5 from which a pipe 6 leads toa suction fan I which serves to withdraw air thru the burnin charge on the pellets and to discharge such air into a stack 8- Th tracks id of the sintering machine are extendedto that the pellets containing hot sintered-,material will travel some distance therealong after combustion ceases and before the sinter is discharged from the palletsv and into a discharge chute- 9. Beneath the pallets, in this extended portion of the tracks are disposed a plurality of suction boxes III which are similar to boxes 4 and which are connected to manifold ll.-

This manifold communicates thru pipe I! with a suction fan I! which serves to draw air thru pending on the result desired, particularly the extent of cooling of the sinter, for the more boxes III that are provided the more air will pass thru the burnt sinter and the lower will be the temperature of the sinter when it reaches the discharge end of the machine.

It will be understood that the amounts of air drawn thru the pallets by fans 7 and I3 may be regulated by controlling the sizes and speeds of these fans. For example, the amount of air drawn thru the pallets above suction boxes 10 may be varied from zero when fan I3 is not operating, to the full capacity of the fan, when it is operating at maximum speed. Furthermore, the speed of these two fans may be regulated independently of, or in accordance with, the speed of the other fan.

In Fig. 2 the manifold 5 is connected to a suction fan I5 by a conduit 18 containing a flowregulating valve II. A relief valve l8 opens into conduit It on the fan side of valve II. The fan I 5 withdraws air from manifold 5 and delivers it into stack 19. The conduit 20 leading from manifold H is provided with a similar flowregulating valve 2| and a similar relief valve 22 and opens into pipe Hi between the valve i7 thereof and fan 15. By adjusting the valves l7 and 22 the amounts of air passing thrusuction boxes (similar to boxes I and Id of Fi 1) connected to manifolds 5 and II may be controlled, the relief valves 18 and 2| serving to admit air into the respective pipes 18 and 20 to relieve the amount of vacuum in either line.

It will be understood that more or less than four suction boxes I 0 may be employed, de-

Altho the sintering machine illustrated in Fig.

1 is of the endless track type, it will be understood that the present invention is not confined to such a machine but may be employed with sintering machines of other .types, for example, the Greenawalt type. One important difference between the prior m chines and amachine embodying the present invention is that cooling air is drawn thru a highly heated charge on a pallet after substantially all the combustible material in the charge has been burned and that such air reduces the temperature of the sinter from about 1000 F. to a temperature of for example about 250 F. before the sinter is discharged from the pallets.

- If desired, manifold l of Fig. 1 may be replaced by two separate manifolds similar to, but only about half the length of, that manifold and connecting each such manifold to the fan 7 by a conduit similar to the conduit I 8 or 20 of Fig. 2. Having thus described the invention so that others skilled in the art may be able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

What is claimed is: In a sintering machine having an endless track, pallets to run on said track, means to ignite combustible material in an ore charge on said pallets, and means to draw air thru a burning charge on a moving pallet and including suction boxes, a manifold, a conduit having a flow regulating valve, a relief valve and a fan operatively connected together, the combination of a cooling zone along the track for pallets whose charges have been burned, and means for drawing cool air thru burned charges on pallets in said cooling zone, said last named means including a plurality of suction boxes, a manifold connected to the boxes, and a conduit having a flow regulating valve and a relief valve and connecting said last named manifold to the aforesaid fan.

ALFRED W. BABB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

